1. Field of the Invention
The present invention relates generally to a solenoid controlled valve, i.e. a electromagnetic valve for use in various kinds of industrial machines utilizing pressure such as oil pressure and air pressure, and more particularly to a solenoid controlled valve of the double pilot type in which a pair of pilot valve units including solenoids are provided on respective sides of a valve main body including a valve mechanism driven by the solenoids.
2. Description of the Related Art
The above mentioned double pilot type solenoid controlled valve has been widely used. In a known solenoid controlled valve, electric wires for supplying driving signals to the solenoids provided in the pilot valve units are separately connected to the pilot valve units. Therefore, in the case of mounting a plurality of valves on a single common manifold, a number of electric wires have to be connected to respective pilot valve units, so that the wire connecting operation is very cumbersome.
In order to make easier the wire connecting operation, Japanese Utility Model Publication, No. 61-126162 proposed therein a solenoid controlled valve in which electric wires can be connected to the valve only from one side thereof. That is to say, a printed circuit board is inserted between a valve main body and a base and one side thereof is extended beyond one pilot valve unit, the electric wires being connected to the extended portion. However, in this known valve, the projected portion of the printed circuit board might be subjected to dust, water, and mechanical stress. These intrusions result in deterioration of the electric connection so that a malfunction of the valve might occur. This drawback would be significant when an electric circuitry for controlling and protecting the valve is arranged on the exposed portion of the printed circuit board as disclosed in Japanese Utility Model Publication, No. 61-124776.
In Japanese Utility Model Publication, No. 61-126163, a printed circuit board is arranged on a top surface of the valve and a cover is provided on the printed circuit board. In this known valve, it is necessary to provide a substantially large space for arranging a connector for the electric wires and thus the whole dimension becomes very large and the cost is liable to increase.